The present invention relates in general to the cooling of computer electronic components by liquid systems. More particularly, the invention relates to a scalable design for liquid cooling of electronics systems, utilizing removable modular pumping units and an integrated plate heat exchanger/expansion tank.
Heat fluxes dissipated by electronic equipment, such as microprocessors and power supplies, are reaching levels that preclude air cooling as a means to control component temperature. Liquid cooling (e.g. water cooling) is a very attractive technology to manage the higher heat fluxes. The liquid absorbs the heat dissipated by the components/modules in a very efficient matter (i.e. with minimal rise from the liquid to the component being cooled). The heat ultimately has to be transferred from the liquid and out of the data center (i.e. room containing the electronic equipment) environment, otherwise, the liquid would continuously rise in temperature. From the 1970s through the early 1990s, IBM accomplished this task back by circulating the cooling liquid (i.e. system water) via a coolant distribution unit (FIG. 1). The system water would flow through a liquid/liquid heat exchanger that was cooled by relatively low temperature water, known as site service or customer water, which was provided by the customer facility. This unit stood separate from the electronics frames and would supply system water (maintained at about 22 C) to one or more electronics frames.
Back when the cooling distribution unit (CDU) was used, a single computer system could fill the entire data center. There was only a need for one CDU design point in terms of heat removal and system water flow rates. However, with current and future systems occupying a single frame, a cooling unit may be called upon to support anywhere from 1 to n number of systems. More importantly, computer customers customarily choose to scale up their computing requirements as their needs grow by adding more electronics within a fame or adding additional electronics frames. It is highly desirable, therefore, to be able to scale up the function of a cooling distribution unit.
Power levels in computer equipment (primarily processors) have risen to the level where they can no longer be air cooled. These components will likely be water cooled. Heat dissipated by the processor will be transferred to the water via a water cooled cold plate. Water typically available at customer locations (i.e. data centers) is not suitable for use in these cold plates. First condensation formation is a concern as the temperature of the data center water, ranging from 7 C to 15 C, is fair below the room""s dew point (typically 18-23 C). Second, the relatively poor quality of the water (its chemistry, cleanliness, etc.) impacts system reliability. It is therefore desirable to utilize a water cooling/conditioning unit that circulates high quality water to/from the electronics to be cooled and rejects the heat to the data center water.
It is also desirable to provide the water cooling function in a considerably smaller volume, preferably within a single 19xe2x80x3 or 24xe2x80x3 rack. It would help to utilize a plate heat exchanger in lieu of the bulky shell and tube heat exchangers used in past systems, but something more is needed in terms of volume reduction. Furthermore, it is desirable to avoid the extra expense and volume associated with insulating the heat exchanger to prevent condensation formation. While some attempt at space consolidation has been made in the past (e.g., as disclosed in patent application entitled xe2x80x9cCooling System for Portable Electronic and Computer Devicesxe2x80x9d by Richard C. Chu et al., Ser. No. 09/893,135, filed Aug. 17, 2001, and assigned to the assignee of the present invention, wherein an expansion space was provided within a heat exchanger in a personal computer environment), these did not deal with the rack-mounted frame environment nor take the novel approach presented herein.
Disclosed herein is the concept of a Scalable Coolant Conditioning Unit (SCCU) which provides the means to scale the function of a CDU. This is accomplished by utilizing modular pumping units that can be added to the SCCU. Additionally, the SCCU takes advantage of an integral heat exchanger/expansion tank that is sized to handle the maximum design point. The modular pumping units are arranged in a parallel flow configuration; additional pumps provide additional flow at a consistent pressure drop. The alternative to this concept would be to design, build, and inventory multiple CDUs and swap in successively larger units as the customer""s requirements grow. It is far more cost effective to apply the concept disclosed here utilizing one common unit with the capability of accommodating multiple pumping units to scale-up flow and cooling capability as the customer""s requirements grow. The SCCU makes cooling water a customer supplied utility providing conditioned water (in terms of temperature and cleanliness) for cooling each flame as needed, much like a municipal water utility distributes water to each home as needed.
Also disclosed herein is the concept of physically integrating a plate beat exchanger within the expansion tank in order to reduce volume and prevent condensation formation on the heat exchanger without having to add bulky insulation.
The recitation herein of desirable objects which are met by various embodiments of the present invention is not meant to imply or suggest that any or all of these objects are present as essential features, either individually or collectively, in the most general embodiment of the present invention or in any of its more specific embodiments.